Transfer switch for high-frequency heating systems



March 6, 1 951 c. E. ELLSWORTH ET AL TRANSFER SWITCH FOR HIGl-LFREQUENCYHEATING SYSTEMS Filed Aug. 20. 1947 4 Sheets-Sheet 1 4 m s Q B A .1. MLmh M E. w Q m\ \h NR ouwpv nh %h V mw 3 Wu R R hm MN Q w MN 8mm. Mm V vwINVEN TORS Gun 5. [LLSWGRTH A TTORNEVS March 1951 c. E. ELLSWORTH ET AL2,543,768

TRANSFER SWITCH FOR HIGH-FREQUENCY HEATING SYSTEMS Filed Aug. 20. 1947 4Sheets-Sheet 2 Km w 5 A M w T Q N s E u w i \M f L R ww Q Mw h NM wh mhWk hm 0H. N1 QM. m\ ms mh F 5 /4/? THUR E. 6/; 55/? 7' B) A TTOR/VEVSMarch 1951 c. E. ELLSWORTH ET AL 2,543,768

TRANSFER SWITCH FOR HIGH-FREQUENCY HEATING SYSTEMS Filed Aug. 20. 1947 4Sheets-Sheet 5 x/wgrv TORS CARL f. Z45W0RTH ARTHUR /LBERT B) ATTORNEYSMarch 6, 1951 I C.'E. ELLSWORTH ET AL 2,543,768

TRANSFER SWITCH FOR HIGH-FREQUENCY HEATING SYSTEMS Filed Aug. 20, 1947 4Sheets-Sheet 4 mug/v TORS CARL 5 LCZLSH/G/FTH A TTOR/VEVS Patented Mar.6, 1951 TRANSFER SWITCH FOR HIGH-FREQUENCY HEATING SYSTEMS Carl E.Ellsworth, Louisville, and Arthur E. Gilbert, near Louisville, Ky,assignors to The- Girdler Corporation, Louisville, Ky., a corporation ofDelaware Application August 20, 1947, Serial No. 769,698

14 Claims.

-1 a This invention relates to transfer switches of the typeparticularly applicable for use with highfrequency heating systemsandhasfor an object the provision of a transfer switch which is rela tivelycompact, rugged in construction, easily operated, and which insuresthecompletion of circuit connections with a minimum of electricalresistance.

In the application of electrical energy to dielectric materials for thegeneration of heat therein, a

relatively high voltages and frequencies are utilized. For example, thevoltage may be of the order offroni 1000 to 50,000 volts with afrequency of the order of. from 1,000,000 cycles per second to10,000,000 cycles pe second, and above. Since the heating effect isproportional to. the square of the voltage and directly to thefrequency, it is desirable for any given installation to utilize high,optimum values of frequency and voltage. This ineans thatthe voltagesinvolved, without provision of safety features, are dangerously high.The conductors are ordinarily of relatively large size and, in general,are included inconcentric lines.

As. explained in Zottu Patent 2,419,307, a transfer switch is essentialif a high-frequency gen.- erator is utilized to supply energy to morethan one load for the reason that the very size of the conductorsmakesdific-ult, if not impractical, the manual connection anddisconnection of such conductors from one load toanother. Thetransfenswitch of said Zottu patent while satisfactory, leaves somethingto be desired in compactness, ease of operation and, the development ofdesired contact pressures.

In carryin out the present invention in one form thereof, there isprovided in circular array around a common center a plurality ofstationary contacts respectively connected to various loads to besupplied with high-frequency energy. A centrally located movable contactmay be fluidcooled through internally located flow channels, thecontact-engaging portion itself consisting of a spherical contactmovable into and out ofengagement with concave surfaces of each of thestationary contacts and presenting to each a dif ferent contact surface;Preferably, a toggle mechanism or equivalent is utilized to develophigh-contact pressures and to eliminatesliding friction during movementfrom one circuit-controlling position to another. The high-vo1tagemovable contact is isolated from the operating mechanism by a pluralityof insulators and is cnnected by aflexible conductor, including aplurality of Sylphon bellows, to the incoming line from thehigh-frequency separator.

For further objects and advantages of the in vention, reference-is to behad to the following descriptiontaken in conjunction with theaccompanying drawings, in-whichthe transfer switch has been illustratedtogether. with a grounding arrangement which forms the subject matterof.a copending application filed. by Austin .Proctor, also-worker of ours,on .AugustZO, 1947, Serial No. 169,660.

In the drawings:

Fig. l is a sectional elevation of a transfer switch embodying theinvention;

Fig. 2 is a sectional view takenonthe line.2.-- of Fig. 1;

Fig. 3 is a fractional view similarto Fig. l but with the parts in anopen circuit position;

Fig. 4 is a view taken on the line 4-4 of Fig. 1; and

Fig. 5 is an isometric View of the switch illustrating the manner inwhich the operating handle projects from the. enclosinghousing.

Referring to the. drawings, the invention inone' form has been shown as;appliedto. atransfer switch comprising a movable contact I0. which; inits preferred-form is-provided withcu-rvedcontact surfaces lea- Asshown,the movable contact It is hollow and spherical, with the. lower: endthereof provided with a stud l l extendingthrough an arm l2 and securedin place bya. nut, l3 located on theouter threaded .end thereof. The arml2 extends from a. supportingmember or bracket. l4 having'a conical orconcavesurface Ma to form a line contact with the. ball-shapedmovablecontact I0. The stud H is loosely dis-.' posedwithin theopeninginxthe arm [2 so that when the supporting member or bracket [4115 movedto the right. against themovable contact it, the concavesurface. l4a,;ispressed againstit. In Fig. 1 th movable contact *is illustrated in onecircuit-controlling position for transfer to energy from a flexibleconductor through movable contact lil'and a-stationary contact l6, byway of the innerconductor l'l'of a concentric line to a selected 'load(not shown) connected thereto. The outer conductor [8 of the concentricline is connected to the housing [9 of the switch, which housing mayinclude angle-supports and 2| fromwhich there'extend insulators 22 and23 for supporting the stationary-contact IS. The stationary contactIii-is also provided with a concave or conical surface l6a which alsoprovides line contact with theball-shaped movable contact l0.

The flexible conductor [5 is'hollow and is made flexible by formingitfrom a series of Sylphon bellows, only four of which, the'bellows,24'2l, are shown. The conductor-Isis secured atone end to aconnector l5c and'forms an extension from the inner conductor 29 ofaiconcentric line, having an outer conductor 30.. The conductors '29 and30 are directly connected to the output terminals of the high-frequencygenerator. The

conductor 29 is of course secured to connector 15c. Themovable'contact'lo may be operated into and out of engagement with anyselected one of the stationary contacts by means of an operating handle3| which includes an actuator 32. To isolate the movable contact ID fromthe operating handle 3|, a plurality of insulators, such as insulators33, 34 and 3Yin' triangular arra extend between the bracket l4 and abracket or member 36 secured to theend of an actuating rod 3']. The rod31, supported in bearings 38 and 39, is connected to one end of a link40 of a toggle mechanism, the other link thereof being formed by anextension of the handle 3| which, it will be observed, is pivoted by ascrew 42 extending through a bracket 43. With the toggle in thestraightened position-as shown in Figs. 1 and 2, there will be developeda very substantial force pressing the movable contact In into linecontact with the stationary contact l6. Upon pressthe latch actuator 32,a latching arm 44 is withdrawn from beneath a part of a rotatable frameor turntable 45. The operating handle 3| may then be moved upwardly, asviewed in Figs. 1, 3 and 5, to rotate its toggle-extension downwardly tobreak the toggle. This movement moves the rod 3'! to the left towithdraw the movable contact ID from engagement wth the stationarycontact l6. 'As this movement occurs, an arm 35a extending from themember 36 rotates an actuating rod 46 in a clockwise direction aroundits pivotal support 41. When this occurs, a compression spring 48,acting on a collar 49 secured to a rod 50, moves the rod to the leftthrough its guides 52 and 53 to rotate a grounding contact arm 54 aboutits pivotal support 55.

The lower end of the arm 54 has a pin 56 extending through it and into aslot 51 formed in an adjustable member carried by the rod 5|]. Thegrounding arm 54, Fig. 4, is provided with four sets of contacts. Thepair of contacts 58, upon clockwise rotation of the arm 54, engagethe'grounded outer conductor I8, Fig. 3, of the concentric line, whilethe pair of contacts 59 resiliently form a wiping engagement with theinner conductor Thus, as the movable contact It! disengages thestationary contact 16, the inner conductor ll of the concentric line andthe housing I?) is grounded in avoidance of all hazards to the operatorat the load which is being disconnected from the high-frequencygenerator.

It will be observed that each of the remaining stationary contacts isprovided with similar grounding arms 54 together with their associatedcontacts and that these are in positions for grounding each of the innerconductors of the lines extending from the transfer switch. By reason ofthese provisions, maximum safety is attained inasmuch as theinterruption of the grounding connection can occur only when there isdeliberate operation of the handle 3| to connect a particular concentricline and load to the high-frequency generator, as to the suppl conductor29.

. It has already been mentioned that the movable contact I!) may befluid-cooled for some applications of the invention. If air beintroduced through a flexible tube 6|] for producing a blast of coolingair against the hollow inner surface of movable contact H], with exitthereof around the outer surface of the flexible tube 60, the resultingair pressure within the bellows 24-28 may tend to elongate them.Accordingly, it is preferred that there be provided one or more tensionmembers to resist elongation of the flexible con- 4 ductor 5. Preferablythe flexible tube 69 is so constructed as itself to resist elongation.For example, it may include either as an integral part thereof orseparately therein tension members such as a cable 6| which resistelongation without materially decreasing the flexibility of conductor l5about the axis of the inner conductor 29. It is further contemplatedthat the tension members themselves may extend between the movablecontact I0 and the connector |5c carried by the supporting plate 62 intowhich the flexible conductor I5 is also secured as by the screws 53. Thetension-resisting elements may be utilized with or without cooling ofcontact l0 and whether or not a liquid be used as a cooling medium inplace of circulation of air, or other cooling gas.

Thus far there has been described the operation of the switch from itsposition illustrated in Figs. 1 and 2 to the position illustrated inFig. 3.

After the operation of the switch to the opencircuit positionillustrated in Fig. 3, the movable contact In may be rotated intoengagement with any selected one of the stationary contacts. Forexample, the handle 3| may be lifted from its position shown in Figs. 1and 5 upwardl and out of an indexing recess 64 and thence along acircumferential slot 65, Fig. 5, formed as a part of the housing I9until it coincides with another indexing slot, such as one of the slots67a, 68a and 63a. Thereupon the handle 3| is moved downwardly tostraighten the toggle and to move the contact I0 into engagement withthe corresponding one of associated stationary contacts 61, 68 or 69,shown in Fig. 2. Of course, any other position may thereafter beselected for operation of the switch.

The movable-contact assembly, Fig. 1, including the turntable or frame45, is rotatably supported on a subframe ID by means of a bearing H ofthe frame 45 which receives a bearing member 12 extending upwardly fromthe subframe 10. A further indexing mechanism is provided by a spring 13which urges a ball 74 into recesses 15 formed in the upper plate of thesubframe 10 in positions corresponding with the locations of thestationary contacts.

Each of stationary contacts |6, 61, B8 and 69 is mounted on the innerconductor of a concentric line, the outer grounded conductors 76, ll, 18and 19 of which are shown in Fig. 2.

It is, of course, to be understood that interlock contacts will beprovided, so that immediately upon upward movement of the operatinghandle 3|, or upon releasing movement of the latch actuator 32, thehigh-frequency generator will be deenergized. Such interlock contactsare conventional, and, therefore, have not been illustrated; see forexample the interlock contacts N9 of the aforesaid Zottu Patent No.2,419,307. Besides personnel protection, it is intended that thehigh-frequency generator shall always be deenergized before operation ofthe selector switch in order to avoid any arcing between the movablecontact ||J and any selected stationary contact.

In the operation of the switch from one circuitclosing position toanother, it is to be observed that the movable contact l0 will rotaterelative to the bracket l4 and its supporting arm II. This isparticularly advantageous since such relative rotation will bring intoregistry with each stationary contact a different contact-engagingsurface of the curved movable contact l0. Thus,

wear on the movable contact ID will be distributed 5. over a substantialpart of the curved surface thereof. This advantageous result isbroughtabout by the pivotal mounting of the movable contact HI- on the arm I2and by reason of the fact that the flexible conductor I5 does not turnor twist about its center line. In other words, it assists in producingthe relative rotary motion of the contact In relative to the arm l2.flexible conductor 15 need not be formed of' a plurality of Sylphonbellows since any flexible conductor may have one end attached to the:

connector I50 and may extend downwardly toward the circular arrayofstationary contacts 16, 61-, 68 and 63,, and thence outwardly and in.

spaced relation with the plane thereof, and thence downwardly to themovable contactv l0. With such a. flexiblev conductor, as I5, themovement. of the free end thereof to whichthei contact; I is secureddescribes an are having a radius some what less than that of thecircular array of stationary contacts. The flexible conductor I not onlyprovides for the circular motion but also for the radial motion duringmovement of contact In: into and out of engagement with. a selectedstationary contact.

While a preferred embodiment of the invention has been illustrated, itisto be understood. that further modifications may be made without.departing from the scope of the appended claims.

What is claimed is:

1. A transfer switch comprising a plurality of stationary contactslaterally spaced one from the: other, a movable contact, a bracket forsupport-- ing, said movable contact for rotation relative to saidbracket, actuating. mechanism for moving said bracket to move saidmovable contact intoand out of engagement with a selected. stationarycontact, a flexible conductor having. one end secured to said movablecontact'and having its opposite end anchored in spaced relation thereto,said flexible conductor being efiective to produce.

relative rotation between said stationary contact.

and said bracket.

2-. A transfer switch comprising. av plurality of stationary contactslaterally spaced one from the other, a movable contact, a bracket forsupport-- ing' said movable contact for rotation relative to saidbracket; actuating. mechanism for moving said bracket to move saidmovable contact. into and out of engagement with a. selected stationarycontact, a hollow flexible conductor having lateral flexibility butresisting rotary movement. about the EtXis. thereof, one end of saidflexible conductor being secured to said movable contact, supportingmeans for said conductor spacedifrom said movable contact and saidbracket, said conductor resisting rotation thereof to bring differentareas of said movable contact. into engage.- ment with each of said.stationary contacts.

3;. A transfer switch comprising a plurality of stationary contacts.laterally spaced one from the other, a hollow spherical movable contact,a bracket for supporting said movable: contact for rotation relative tosaid bracket, actuating mechanism for moving said bracket to move saidmovable contact into and out of engagement with a selected stationarycontact, a hollow flexible conductor of construction providing lateralflexibility but resisting rotary movement about the axis. thereof, oneend of said, flexible conductor being secured tosaid movable contact andresistingv rotation thereof to; bring difierent areas of. said movablecontact into. engagement with each of. said stationary contacts, and; aflexible fluid conextending lengthwise of said flexible, con.

The

ductor for flow of a coolant into and out of said hollow contact in heatexchange therewith.

4. A transfer switch comprising a sperical movable contact, a pluralityof stationary contacts spaced one from the other in circular arrayaround said movable contact, means including an operating mechanismrotatably supporting said movable contact for movement into alignmentwith any selected one of said stationary contacts, said operatingmechanism including means connected to said movable contact for movingit generally radially toward and away from a selected stationary contactand for developing high contact pressures when said movable contactengages astationary contact and for relieving that pressure as saidmovable contact disengages a stationary contact, said operatingmechanism including a pivotal support for movement of said:

mechanism and saidmovable contact from one: stationary-contact position.to another, and aflexible conductor connected to and movable with saidmovable contact but which resist rotation about. its own axis to producerelative rotation. between. said movable contact and said operatingmechanism as the. latter is moved from one stationary contact positionto another to present different areas of said movable contact to each ofsaid stationary contacts.

5:. The combination set forth in claim 4 in which each of saidstationary contacts is provided with a conical surface for engagement bysaid movable contact and said operating mechanism is provided with, apressure-applying member having a conical surface for engaging said:movable contact.

6. A transfer switch comprising. a plurality of stationary contactsspaced one from the other in a common plane and in circular array abouta common axis, a supply conductor spaced outwardly from said commonplane of said stationary contacts with the adjacent end thereofsubstantially concentric with said common axis, a flexible conductorconnected at one end to said adjacent end of said supply conductor andextending'both axially toward and radially outward from said common axisto a point adjacent to, but within the radius of, said circular array ofsaid stationary contacts, a movable contact, having aspherical contactsurface, connected to the free end of said flexible conductor, operatingmechanism, means supporting said mechanism for rotation about saidcommon axis, said opcrating mechanism including insulating meansinterposed between said axis and said movable contactfor electricallyinsulating the latter from the remainder of said mechanism but servingas a. mechanical connection between said movable contact andsaidremainder of said mechanism, the disposition and flexibility of saidflexible conductor providing for movement thereof. with said.

movable contact about said circular array of stationary contacts.

7. A transfer switch comprising a plurality of. stationary contactsspaced one from the other in circular array about a common axis, amov--able. contact, each of said stationary contacts and. said. movablecontact having curved contactengaging surfaces for nesting relation oneWith the other, a pivoted supporting member having spaced: guides, anactuating member carried by said guides and slidable with respectthereto in. directions normal to said axis; means including saidactuating member for supporting said. movable contact and for moving. itinto and out of abutting: engagement-with. a. selected stationarycontact, an Operating handle pivotall connected to said supportingmember and to said actuating member for rotating said supporting memberand said rnOVable contact from one to another of said stationarycontacts, a flexible conductor directly connected at one end to saidmovable contact, and means supporting aid flexible conductor in spacedinsulated relation with said pivoted support and from said actuatingmember for movement of said end with said movable con-- tact from one toanother of said stationary contacts.

8. A transfer switch comprising a plurality of stationary contactsspaced one from the other in circular array about a common axis, amovable contact, each of said stationary contacts and said movablecontact having concave and convex contact-engaging surfaces for nestingrelation one with the other, a pivoted supporting member having spacedguides, an actuating member carried by said spaced guides and slidablewith respect thereto in directions normal to said axis, means includingsaid actuating member for supporting said movable contact and for moving it into and out of abutting engagement with a selected stationarycontact, an operating handle pivotally connected intermediate its endsto said supporting member, a link the respective ends of which arepivotally connected to one end of said operating handle and to one endof said slidable actuating member to form a toggle for rotating saidsupporting member and said movable contact from one to another of saidstationary contacts, a flexible conductor directly connected at one endto said movable contact, means supporting said flexible conductorincluding its other end in spaced insulated relation with said pivotedsupport and from said actuating member for movement of said end withsaid movable contact from one to another of said stationary contacts, anindexing member having a slot to receive said handle when said movablecontact is in alignment with a selected stationary contact, saidmovement of said handle into said slot straightening said toggle to movesaid movable contact into nesting relation with said selected stationarycontact and to apply substantial contact pressure thereto, said handleupon being lifted from said slot breaking said toggle and withdrawingsaid slidable member and said movable contact from engagement with astationary contact preparatory to rotation of said movable contact intoalignment with another selected stationary contact.

9. A transfer switch comprising a plurality of stationary contactsspaced one from the other in circular array about a common center, amovable contact having a curved contact surface, operating mechanism formoving said movable contact into and one of engagement with a selectedstationary contact and when out of engagement with a selected contactfor moving it from one stationary contact to another, means supportingsaid operating mechanism for rotation about an axis extending throughsaid center and normal to the plane of said circular array of stationarycontacts, means for connectin said movable contact to a source of supplycomprising supporting means spaced outwardly from said plane of saidstationary contacts and substantially in alignment with said axis, saidmeans including a flexible conductor extending downwardly toward saidplane and outwardly in spaced relation with it and into conductiverelation with said movable contact, said operating mechanism includingmeans for rotatably supporting said movable contact generally in saidplane of said stationary contacts, and means including said conductorfor holding said movable contact in fixed relation with respect to saidflexible conductor for presentation of different surface areas thereofto each of said stationary contacts when operated into selectedengagement therewith.

10. A transfer switch for high voltage, highfrequency electrical energycomprising a plurality of stationary contacts spaced from each other incircular array around a common center, a supply connector for a supplyline spaced outwardly from the plane of said stationary contacts andsubstantially concentric with an axis extending normal to said plane andfrom said common center, a flexible conductor connected at one end tosaid connector and extending toward said plane, thence outwardly thereofand in spaced relation therewith, and thence downwardly to a point nearsaid plane, the free end thereof being radially within said circulararray of stationary contacts, a movable contact of spherical shapeconnected with said free end and disposed in said plane, means includinga bracket supporting said movable contact for rotation with respectthereto, said bracket and each of said stationary contacts havingconically shaped surfaces for line contact-engagement with said movablecontact, insulating means supporting and extending from said brackettowards said center, a turntable rotatable about said axis, andoperating mechanism carried by said turntable and connected to saidinsulating means for actuation of said movable contact into and out ofengagement with a selected one of said stationary contacts and rotatablewith said turntable for rotation of said movable contact from oneselected stationary contact to another selected stationary contact, saidconductor restraining said movable contact for relative rotation withrespect to said bracket to bring a different contact surface thereofopposite each of said stationary contacts.

11. A transfer switch for high-voltage highfrequency electrical energycomprising a centrally disposed input conductor forming the innerconductor of a high-frequency electrical concentric line, a movablecontact, a frame mounted for rotation about an axis substantiallyconcentric with that of said inner conductor, actuating means carried bysaid frame, said actuating means having an insulated bracket rotatablysupporting said movable contact in electrical isolation from said frame,said actuating means also having an operating lever extendingdiametrically outwardly from said actuating means for rotating saidframe, said actuatin means and said movable contact from onecircuit-engaging position to another, said actuating means including atoggle mechanism for developing high-contact pressures between saidmovable contact and an associated stationary contact, and a flexibleconductor connected at one end to said inner conductor and at its otherend to said movable contact, said flexible conductor including aplurality of Sylphon bellows to impart flexibility thereto for alldirections of movement resulting from movement of said movable-contactstructure from one stationary contact to another and into and out ofengagement therewith.

12 The combination set forth in claim 11 in which said movable contactis hollow, and in which said flexible conductor includesfluidtransmitting means for flow of a stream of cooling fluid into heatexchange relation with said movable contact, and thence outwardlytherefrom for minimizing rise in temperature thereof.

13. A transfer switch comprising a movable contact and at least onestationary contact, means including an operating mechanism rotatablysupporting said movable contact for movement into alignment with saidstationary contact, said movable contact being hollow, a hollowfluidconducting flexible conductor connected to said movable contact forflow of current thereto, and a fluid-conducting conduit disposed withinsaid hollow conductor for flow of cooling fluid directly into heatexchange relation with said movable contact for cooling the same andoutwardly therefrom in the space between said flexible conductor andsaid conduit disposed therein.

14. A switch comprising a movable contact of spherical shape, aplurality of stationary contacts in circular array around said movablecontact, each of said stationary contacts having a conical circuitmaking surface, an actuating member rotatably supporting said sphericalcontact and having a conical surface for engaging said sphericalcontact, means for moving said actuat- 10 ing member to bring itsvconical surface into diametral alignment with said spherical contact andthe conical surface of a selected stationary contact, and means attachedto said spherical contact for producing relative movement with respectto said actuating member for a different diametral alignment throughsaid spherical contact for each circuit making position thereof.

CARL E. ELLSWORTH. ARTHUR E. GILBERT.

REFERENCES CITED The following references are of record in the flle ofthis patent:

UNITED STATES PATENTS

